Security firm G4S has said the contract to provide security for the London 2012 Olympic Games has cost it £50m.The figure is at the top end of the scale of losses the company had warned it would bear, after it failed to recruit and train enough of the guards it had promised for the event.The government was forced to turn to the military for the extra staff, for which G4S confirms it will pay.G4S chief executive Nick Buckles has apologised for the debacle.G4S revealed the cost along with its interim results, where it said half-year pre-tax profits had fallen from £151m to £61m.The company’s contract was worth £284m and included the supply of 10,400 security guards to the 100 Olympic sites across the country. However, the company was unable to recruit enough in time. Less than a month before the opening ceremony, it told the government it would not be able to provide enough staff. ParalympicsG4S said in a statement that it had had 8,000 staff on the ground over the course of the Olympics and it had delivered 83% of contracted shifts.It added that in many cases, the military were able to withdraw from specific sites. Its statement said its board was reviewing the contract with the help of the consultants PricewaterhouseCoopers. One of its aims was to examine why failures relating to the Olympic contract were not identified "in a more timely manner”.